Phenolic compound end capped polyester carbonate

ABSTRACT

A composition comprising a copolyestercarbonate derived from a dihydric phenol, a carbonate precursor, and an aliphatic alpha omega dicarboxylic acid or ester precursor wherein the dicarboxylic acid or ester precursor has from 10 to about 20 carbon atoms, inclusive, and is present in the copolyestercarbonate in quantities of from about 2 to 30 mole percent of the dihydric phenol.

This is a divisional of co-pending application Ser. No. 07/627,517,filed on Dec. 14, 1990, abandoned, which is a continuation-in-part ofapplication Ser. No. 07/476,068, filed on Jan. 30, 1990, now abandoned,which is a continuation-in-part of Ser. No. 07/455,118, filed on Dec.22, 1989, also abandoned.

BACKGROUND OF THE INVENTION

Polycarbonates are well known as a tough, clear, highly impact resistantthermoplastic resin. However the polycarbonates are also possessed of arelatively high melt viscosity. Therefore in order to prepare a moldedarticle from polycarbonate, relatively high extrusion and moldingtemperatures are required. Various efforts throughout the years toreduce the melt viscosity while also maintaining the desired physicalproperties of the polycarbonates have been attempted. These methodsinclude the use of plasticizers, the use of aliphatic chain stoppers,reduction of molecular weight, the preparation of bisphenols having longchain aliphatic subtituents and various polycarbonate copolymers as wellas blends of polycarbonate with other polymers.

With respect to plasticizers, these are generally used withthermoplastics to achieve higher melt flow. However usually accompanyingthe plasticizer incorporation into polycarbonate compositions areundesirable features such as embrittlement and fugitive characteristicsof the plasticizer.

Increased flow can be fairly readily obtained with the use of aliphaticchain stoppers, however impact resistance as measured by notched izoddrops significantly. Embrittlement may also be a problem.

When utilizing a bisphenol having a lengthy aliphatic chain thereon,increases in flow can be observed. However these are usually accompaniedby substantial decreases in the desirable property of impact strength.

Reducing the molecular weight of polycarbonate has also been useful toincrease flow for applications requiring thin wall sections. However,molecular weight reduction is limited in the extent that it can bepracticed before properties such as ductility and impact strength areseverely hampered.

Blends of polycarbonate with other polymers are useful to increase meltflow, however the very useful property of transparency is generallylost.

With respect to polycarbonate copolymers it has been well known that areduced glass transition temperature Tg, can be obtained by introducingaliphatic ester fragments into the polycarbonate backbone. Examples ofthis work go back as early as the original copolyestercarbonate patentof Goldberg, U.S. Pat. No. 3,169,121 wherein at column 3, line 64 tocolumn 4, line 41 various aliphatic dibasic acids are disclosed as beingappropriate for usage in making copolyestercarbonates. Reduced softeningpoints are noted. At column 4, line 11, azelaic and sebacic acids aredisclosed. At column 7, example 4, a 50 mole percent ester contentbisphenol-A copolyestercarbonate based on bisphenol-A using azelaic acidas the ester linkage is disclosed. Various other patents since that timehave broadly disclosed the use of aliphatic acids in the preparation ofcopolyestercarbonates for example U.S. Pat. No. 3,030,331, 4,238,596,4,238,597, 4,504,634, 4,487,896 and 4,252,922. Kochanowski U.S. Pat No.4,286,083, specifically refers to the making of a copolyestercarbonateutilizing hisphenol-A, azelaic acid and phosgene in example 6 at column9. 25 mole percent of the azelaic acid, based on the moles ofhisphenol-A, was contacted with the bisphenol-A together with phenol asa chain stopper, and triethylamine as a catalyst in an interfacialreaction with phosgene wherein the pH was maintained at 6 over a periodof 35 minutes and then raised to 11.4 for a period of 36 minutes.Generally these copolyestercarbonates with aliphatic linkages havesignificantly lowered Tgs than the polycarbonate and therefore areprocessable at lower temperature. However, these polymers as inKochanowski do not have other physical properties reported, inparticular impact resistance or impact resistance under variousenvironmental conditions such as heat aging and/or reduced temperature.

Chain stoppers have been utilized in making polymers for many decades.The function of the chain stopper in the preparation of the polymer isto control the molecular weight. Generally these chain stoppingcompounds are monofunctional compounds similar to the functionality of arepeating unit of the polymer. For quite some time scant attention wasdirected to the structure of the chain stopping agent other than it bereactive with the monomer unit during the preparation of the polymer andbe compatible with the polymer. In the last few years more attention hasbeen directed to the structure of the chain stopper. It has been foundthat the structure of the chain stopping compound can significantlyeffect the property spectrum of the polymer. For many years, phenol hadbeen the standard chain stopping agent used in the preparation ofpolycarbonate. At times paratertiarybutylphenol was employed as a chainstopping agent. Lately more attention has been focused on othermaterials for preparation of the polycarbonate. U.S. Pat. No. 4,269,964,disclosed the usage of isooctyl and isononyl substituted phenols aschain stoppers for polycarbonate. Additionally paracumylphenol andchromanyl compounds have been utilized to chain stop polycarbonates.Both the paracumylphenol and chromanyl compounds have been utilized tochain stop copolyestercarbonates wherein there is a totally aromaticmolecule with high ester content, see U.S. Pat. No. 4,774,315 and4,788,275. Accompanying the usage of the larger sized endgroups has beenthe ability to obtain the same or essentially the same physicalcharacteristics of the polycarbonate but at a lower molecular weight.This lower molecular weight provides better flow than a polycarbonate ofa higher molecular weight. However these systems reach a point whereinthe chain stopping agent cannot solve the problems caused by utilizing ashorter chain length, i.e., lower molecular weight polycarbonate.Embrittlement occurs, therefore there still exists a need for a polymerhaving lower processing temperature but which is accompanied bysubstantially increased flow and essentially the full spectrum ofpolycarbonate properties.

A new polymer system has now been discovered which manages to combineexcellent processability due to its extremely high melt flow withessentially maintained physical properties such as toughness,transparency, and impact resistance.

SUMMARY OF THE INVENTION

In accordance with the invention there is a composition comprising acopolyestercarbonate polymer derived from a dihydric phenol, a carbonateprecursor and an aliphatic alpha omega dicarboxylic acid or esterprecursor wherein the dicarboxylic acid has from ten to about twentycarbon atoms, inclusive and the dicarboxylic acid is present in thecopolyestercarbonate in quantities of from about 2 to 30 mole percent ofthe dihydric phenol.

A further aspect is the copolyestercarbonate of the invention extendedto include dicarboxylic acids of 8 and 9 carbon atoms, which isendcapped with a monophenolic compound which provides thecopolyestercarbonate with better Notched Izod impact resistance andductility after aging than the phenol endcapped copolyestercarbonate.

DETAILED DESCRIPTION OF THE INVENTION

Dihydric phenols which are useful in preparing the copolyestercarbonateof the invention may be represented by the general formula ##STR1##wherein: R is independently selected from halogen, monovalenthydrocarbon, and monovalent hydrocarbonoxy radicals;

R¹ is independently selected from halogen, monovalent hydrocarbon, andmonovalent hydrocarbonoxy radicals;

W is selected from divalent hydrocarbon radicals, ##STR2## n and n¹ areindependently selected from integers having a value of from 0 to 4inclusive; and

b is either zero or one.

The monovalent hydrocarbon radicals represented by R and R¹ include thealkyl, cycloalkyl, aryl, aralkyl and alkaryl radicals. The preferredalkyl radicals are those containing from 1 to about 12 carbon atoms. Thepreferred cycloalkyl radicals are those containing from 4 to about 8ring carbon atoms. The preferred aryl radicals are those containing from6 to 12 ring carbon atoms, i.e., phenyl, naphthyl, and biphenyl. Thepreferred alkaryl and aralkyl radicals are those containing from 7 toabout 14 carbon atoms.

The preferred halogen radicals represented by R and R¹ are chlorine andbromine.

The divalent hydrocarbon radicals represented by include the alkylene,alkylidene, cycloalkylene and cycloalkylidene radicals. The preferredalkylene radicals are those containing from 2 to about 30 carbon atoms.The preferred alkylidene radicals are those containing from 1 to about30 carbon atoms. The preferred cycloalkylene and cycloalkylideneradicals are those containing from 6 to about 16 ring carbon atoms.

The monovalent hydrocarbonoxy radicals represented by R and R¹ may berepresented by the formula--OR² wherein R² is a monovalent hydrocarbonradical of the type described hereinafore. Preferred monovalenthydrocarbonoxy radicals are the alkoxy and aryloxy radicals.

Some illustrative non-limiting examples of the dihydric phenols fallingwithin the scope of Formula II include:

2,2-bis(4-hydroxyphenyl)propane (bisphenol-A);

2,2-bis(3,5-dibromo-4-hydroxyphenyl)propane;

2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;

1,1-bis(4-hydroxyphenyl)cyclohexane;

1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane;

1,1-bis(4-hydroxyphenyl)decane;

1,4-bis(4-hydroxyphenyl)propane;

1,1-bis(4-hydroxyphenyl)cyclododecane;

1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclododecane;

4,4-dihydroxydiphenyl ether;

4,4- thiodiphenol;

4,4-dihydroxy-3,3-dichlorodiphenyl ether; and

4,4-dihydroxy-2,5-dihydroxydiphenyl ether.

Other useful dihydric phenols which are also suitable for use in thepreparation of the above polycarbonates are disclosed in U.S. Pat. Nos.2,999,835; 3,028,365; 3,334,154; and 4,131,575, all of which areincorporated herein by reference.

The carbonate precursor utilized in the invention can be any of thestandard carbonate precursors such as phosgene, diphenyl carbonate andthe like. When using an interfacial process or a bischloroformateprocess it is also preferred to use a standard catalyst system wellknown in the synthesis of polycarbonates and copolyestercarbonates. Atypical catalyst system is that of an amine system such astertiaryamine, amidine or guanidine. Tertiaryamines are generallyemployed in such reactions. Trialkylamines such as triethylamine aregenerally preferred.

The monomer which supplies the ester units in the copolyestercarbonateis an aliphatic alpha omega dicarboxylic acid from 10 to about 20 carbonatoms preferably 10 to 12 carbon atoms. The aliphatic system is normal,branched or cyclic. Examples of the system include sebacic acid,dodecanedioic acid, C14, C18 and C20 diacids. The normal saturatedaliphatic alpha omega dicarboxylic acids are preferred. Sebacic anddodecanedioic acid are most preferred. Mixtures of the diacids can alsobe employed. It should be noted that although referred to as diacids,any ester precursor can be employed such as acid halides, preferablyacid, chloride, diaromatic ester of the diacid such as diphenyl, forexample the diphenylester of sebacic acid. With reference to the carbonatom number earlier mentioned, this does not include any carbon atomswhich may be included in the ester precursor portion, for examplediphenyl.

The copolyestercarbonates of the invention can be prepared by the knownmethods, for example those appearing in Quinn 4,238,596 and Quinn andMarkezich 4,238,597. Examples of such processes include the formation ofacid halides prior to the reaction of the ester forming group with thedihydric phenol and then followed by phosgenation. Still further, thebasic solution process of Goldberg in the 3,169,121 reference utilizinga pyridine solvent can also be employed while also using thedicarboxylic acid per se. A melt process utilizing the diesters of thealpha omega dicarboxylic acids can also be employed. An example of sucha compound is the diphenylester of sebacic acid.

After substantial experimentation, it has been found that a preferredprocess for making the copolyestercarbonates of this invention exists.The process of Kochanowski, U.S. Pat. No. 4,286,083 (083) was initiallyutilized and then improved upon. It was found that lower diacids such asadipic acid were not incorporated into the polymer backbone to any greatextent. Rather, one had to go up to higher carbon atom dicarboxylicacids before any significant incorporation of diacid into the backbonewas observed. We have found that the dihydric phenol and alpha omegadiscid should be phosgens ted at a pH of at about 8 to 9 for about 70 to95of the phosgenation. Following that, the pH of the reaction should beraised to a level of about 10 to 12 preferably 10.2 to 11.2 for theremainder of the phosgenation. A preequilibration of the reactants,other than phosgene, at the initial reaction pH, 8 to 9, preferably 8 to8.5, for a period of time, for example 3 to 10 minutes, seems to improvethe incorporation of the diacid into the polymer. On a lab scale whereinthe mixing is not as effective as in a resin reactor, dodecanedioic acidappears to incorporate better when it is used in fine particle size, forexample about 50 to 300 mesh. In per forming this interfacial reaction,the reactor should also contain a catalytic quantity of an amine,preferably triethylamine. Amine catalyst with a range of about 0.75 toabout 3 mole percent based on the dihydric phenol content can beemployed.

Further experimentation has shown that reaction time can besubstantially reduced and the diacid totally or substantiallyincorporated within the copolyestercarbonate as well by utilizing in theinterfacial reaction a solution of the dicarboylic acid salt. That is, asolution of the dicarboxylic acid salt is charged to the reactor ratherthan the dicarboxylic acid per se. Acids of 10 carbon atoms or greaterare preferred. It is of course, preferred to prepare a solution of thesame dicarboxylic acid salt as is being utilized as the aqueous mediumin the interfacial reaction. For example when aqueous sodium hydroxideis used as the aqueous phase in the interfacial reaction as well ascontrol the pH of the reaction, the sodium salt of the dicarboxylic acidis prepared. Other salts can be used such as prepared from potassium,calcium and the like. This is simply done by contacting the diacid,usually in its solid form, with aqueous sodium hydroxide and pumpingthat solution into the reactor. The dihydrlc phenol can be alreadypresent together with the aqueous base and endcapping agent. Thecarbonate precursor such as phosgene is added and the reaction allowedto proceed.

Interestingly with the use of the diacid salt solution theaforementioned pH periods are substantially changed. A period of time ata high pH, about 10 to 12, should still be used to obtain the desiredproduct. However the quantity of time at the lower pH, 8 to 9 can besignificantly reduced. For example when the entire reaction was run atpH 10 with previously prepared sodium dodecanedioate for a period ofonly twenty minutes, 99 percent of the acid was incorporated into thecopolyestercarbonate. When only 25% of the twenty minute reaction periodwas held at pH 8, the remaining 15 minutes at pH 10, and utilizing thepreviously prepared sodium dodecanedioate 100% of the acid wasincorporated into the copolyestercarbonate. Therefore, anywhere fromabout 0 to about 95% of the carbonate precursor addition time should berun at about pH 8 to 8.5 with the remainder of the carbonate precursoraddition time being at a pH of about 10 to 12. Preferably the initialperiod of carbonate precursor addition is from about 5 to 85%.

In order to control molecular weight, it is standard practice to utilizea chain stopping agent which is a monofunctional compound. This compoundwhen reacting with the appropriate monomer provides a non-reactive end.Therefore the quantity of chain stopping compound controls the molecularweight of the polymer. Bulklet chain terminators than phenol shouldprovide substantially better physical properties such as low temperatureimpact. Examples of these bulklet substituents includeparatertiarybutylphenol, isononyl phenol, isooctyl phenol, cumyl phenolssuch as mete and paracumyl phenol, preferably paracumyl phenol, as wellas chromanyl compounds such as Chroman I.

The copolyestercarbonate of this invention with the standard endcappingreagent possesses a substantially lowered glass transition temperature,Tg, therefore providing processability at a lower temperature.Surprisingly accompanying this lower temperature processability aresubstantially equivalent physical properties as a standard polycarbonateof the same intrinsic viscosity as the inventive composition and veryhigh flow rates. When utilizing the bulklet endgroups, it is possible toachieve even lower molecular weight copolyestercarbonate whilemaintaining excellent physical properties such as aged impact resistanceand/or low temperature impact resistance while having a very high flowrate. This allows the copolyestercarbonates of this invention to beutilized where the characteristics of polycarbonates such as clarity,impact resistance, modulus, and overall toughness are required but mustalso be present in increased processability through an enhanced flowrate. Such applications include optically pure materials such as audiodiscs, digital discs, other media storage devices, packaging materials,other thin walled parts and films, optical discs including fiber opticsand the like.

The aliphatic alpha omega dicarboxylic acid ester is present in thecopolyestercarbonate in quantities from about 2 to 30 mole percent,based on the dihydric phenol. Generally with quantities below about 2mole percent the Tg is insufficiently lowered and significantly alteredflow rate is not observed. Above about 30 mole percent, the physicalproperties of the copolyestercarbonate are significantly hindered incomparison to the polycarbonate without the aliphatic ester linkages.Preferred mole percents of aliphatic alpha omega dicarboxylic acid esterare from about 5 to 25 and more preferably about 7 to 15 mole percent ofthe dihydric phenol.

The weight average molecular weight of the copolyestercarbonate cangenerally vary from about 10,000 to about 100,000 as measured by GPCusing a polystyrene standard, corrected for polycarbonate. A preferredmolecular weight is from about 18,000 to about 40,000.

EXAMPLE 1 A. Preparation of Copolyestercarbonate with Sebacic Acid andStep Wise pH Process

To a 100-liter, glass vessel was added deionized water (30 L), methylenechloride (35 L ), bisphenol-A (BPA ) (11.34 K g, 49.68 mol), p-cumylphenol (319 g, 1.50 mol), triethylamine (70 mL, 0.90 mol), sebacic acid(1005 g, 4.97 tool), and sodium gluconate (17.5 g). Phosgene wasintroduced to the reaction mixture at a rate of 150 g/rain for 34 rain(6600 g, 66.73 tool) while maintaining a pH range of 8.0-8.5. The pH wasadjusted to 10. 0 and the phosgenation continued for 10 min.

The phosgene free solution was diluted to 10% solids with the additionof methylene chloride (ca. 45 L) and the polymer solution was extracteduntil solution organic chloride levels were non-detectable andtriethylamine content was less than 1 ppm.

The extracted polymer solution was isolated by steam precipitation at a1.9 L/rain feed rate and 100 psig stream feed pressure. The water wet,coarse powder was chopped in a Fitzmill to achieve a more uniformparticle size and dried in a hot nitrogen fed fluid bed drier with thetemperature at 110° C. maximum.

The copolyestercarbonate resin had a Tg of about 128° C. Standardpolycarbonate has a Tg of 150° C. Extrusion at 230° C. and molding at275° C. yielded a transparent material which exhibited improved flow andat 300° C. (g/10 rain) processability, MFI=15, as well as excellentmechanical properties. The 1/8" notched izod was 880 J/M, the DTULmeasured at 1.8s MPa was 119° C.

B. Preparation of Copolyestercarbonate with the Earlier Prepared Salt ofDDDA

The disodium salt of dodecanedioic acid (DDDA) was generated bydissolving the free acid (7.2 g, 31 mmol) and NaOH pellets (2.7 g, 68mmol) in water (180 mL).

A 2000 mL five neck Morton flask equipped with a bottom outlet wasfitted with a mechanical stirrer, a pH probe, an aqueous sodiumhydroxyde (50%) inlet tube, a Claisen adapter to which dry ice condenserwas attached, and a gas inlet tube. The flask was charged with bisphenolA (71 g, 311 retool), triethylamine (0.9 mL), p-cumylphenol (2.0 g, 9retool), methylene chloride (220 mL), and the disodium salt solution ofDDDA described above. Then phosgene was introduced at a rate of 2g/rain, while the pH was maintained at 8 by addition of caustic for 10minutes; the pH was then raised and maintained at around 10.5 whilephosgene addition continued for 10 additional minutes. The total amountof phosgene added was 40 g (400 mmol). The pH was adjusted to 11-11.5and the organic phase was separated from the brine layer and washed with2% hydrochloric acid (3×300 mL), and with deionized water (5×300 mL).

The brine layer was acidified to pH 1 with concentrated HC1 and nounreacted DDDA precipitated.

The solution was dried (MgSO₄), filtered, and then precipitated intomethanol (1500 mL). The resin was washed with methanol (1×500 mL) anddeionized water (4×500 mL), and dried at 100° C. for 15 hours.

EXAMPLES 2-6

To a 100-liter, glass vessel was added deionized water (30 L), methylenechloride (35 L), BPA (11.34 Kg, 49.68 mol), p-cumyl phenol (319 g, 1.50mol), triethylamine (70 mL, 0.90 tool), dodecanedioic acid (1155 g, 4.97tool), and sodium gluconate (17.5 g). Phosgene was introduced to thereaction mixture at a rate of 150 g/min for 34 min (6600 g, 66.73 mol)while maintaining a pH range of 8.0-8.5. The pH was adjusted to 10.0 andthe phosgenation continued for 10 min.

The phosgene free solution was diluted to 10% solids with the additionof methylene chloride (ca. 45L) and the polymer solution was extracteduntil solution organic chloride levels were non-detectable andtriethylamine content was less than 1 ppm.

The extracted polymer solution was isolated by steam precipitation at1.9 L/min feed rate and 100 psig stream feed pressure. The water wet,coarse powder was chopped in a Fitzmill to achieve a more uniformparticle size and dried in a hot nitrogen fed fluid bed drier with thetemperature at 110° C. maximum.

The copolyestercarbonate resin had a Tg of about 125° C. Extrusion at250° C. and molding at 275° C. yielded a transparent material whichexhibited improved flow and processability, MFI=13 at 300° C. (g/10min), compared to standard polycarbonate of similar or same molecularweight, as well as excellent mechanical properties. The 1/8" NotchedIzod was 880 J/M, the DTUL measured at 1.82 MPa was 119° C.

Copolymers of various intrinsic viscosities containing 10 mol %dodecanedioyl ester were prepared according to this procedure. Thecopolyestercarbonates were paracumylphenol-endcapped. Thecopolyestercarbonates were compared to standard commercial grade BPApolycarbonates, Lexan 125, 145, and 135 prepared by GE Plastics, all ofwhich were phenol end-capped, as well as stearic acid endcappedpolycarbonate (SAPC) of a similar intrinsic viscosity. All materialswere stabilized with 0.05 weight percent of a phosphite.

                                      TABLE                                       __________________________________________________________________________    Example      3   4   5   6   SAPC                                                                              SAPC                                                                              125 145 135                              __________________________________________________________________________    IV (dl/g)     0.51                                                                              0.48                                                                              0.53                                                                              0.62                                                                              0.48                                                                              0.53                                                                              0.48                                                                              0.52                                                                              0.63                            MFI (g/10 min) at 300° C.                                                            32  46  27  13  34  19  18  11  5                               Tg (C.)      124 124 123 127 126 131 149 149 150                              HDT (1.82 MPa) °C.                                                                  116 117 118 119 116 123 138 140 142                              INI* (J/m)   781 704 772 883 64 (B)                                                                            96 (B)                                                                            728 770 875                              Tens Y (N/mm)                                                                              56.4                                                                              57.4                                                                              56.3                                                                              55.4                                                                              62.1                                                                              62.6                                                                              61.5                                                                              60.7                                                                              59.1                             % Elongation 130  81 120 150 103 104 129 110  98                              __________________________________________________________________________     *Notched Izod                                                            

In general the copolyestercarbonates of the invention have substantiallylower glass transition temperatures and heat deflection temperaturesthan the standard polycarbonates. In fact they were very similar to thestearic acid endcapped polycarbonate comparative examples. However thesestearic acid endcapped materials were extremely embrittled in comparisonto the normal polycarbonate and the copolyestercarbonates of theinvention. The invention materials demonstrated outstanding flowrelative to the standard polycarbonates while achieving equivalentimpact resistance.

In the Table below, Example 4 of the invention is compared to a standardBPA polycarbonate but containing either 7 weight percent of adiphosphate plasticizer or in admixture with a 10 wt. % of polybutyleneterephthalate.

    ______________________________________                                                        MFI (g/10 min)                                                                          125 NI Trans-                                       Example     IV     Tg     300° C.                                                                          mission (J/M)                             ______________________________________                                        4           0.48   124    46        883(D)*                                                                              90                                 7% CR733S   0.50   128    45         50(B)*                                                                              90                                 10% PBT BLEND                                                                             0.49   126    45         50(B)*                                                                              89                                 ______________________________________                                         *D is a ductile break, B is a brittle break                              

As is clearly observed from the above data, the presence of theplasticizer or the polyester brings about similar flows andtransparancies but seriously embrittles the polycarbonate in comparisonto the copolyestercarbonate of the invention.

EXAMPLES 7-9

Following procedures similar to Example 2, bisphenol-Acopolyestercarbonates incorporating the same quantity of dodecanedioicacid and varying quantities of p-cumylphenol endcapper were prepared.The properties of these paracumyl-endcapped copolyester- carbonates werecompared to a paracumylphenol endcapped bisphenol-A polycarbonatecontrol. The results are provided below wherein there is 10 mole percentdodecane- dioic acid ester in the copolyestercarbonate, I.V. isintrinsic viscosity measured at 25° C. in methylene chloride, Mw isweight average molecular weight measured by GPC. MFI is Melt Flow Indexat 300° C. (g/10 min). Y.I. is yellowness index measured according toASTM D1925, and N.I. is notched izod impact strength measured accordingto ASTM D256 at room temperature (RT) and -10° C. All breaks were 100%ductile of all five samples except for control at -10° C. which was 100%brittle.

    ______________________________________                                                                N.I. (J/M)                                            Example                                                                              I.V.   Mw       MFI  Tg C.  Y.I. RT -10° C.                     ______________________________________                                        Control                                                                              .439   22,000   22   149    --   623   156                             7      .495   27,766   16   130    1.9  831   779                             8      .488   26,363   25   125    1.7  831   779                             9      .456   21,717   48   125    1.9  623   675                             ______________________________________                                    

As is observed from the above results, standard "high flow"paracumylphenol endcapped polycarbonate, the control, exhibitedreasonable flow, MFI=22, at a molecular weight of about 22,000. However,the Notched Izod at -10° C. is low and completely brittle. Thecopolyestercarbonates of the invention, however, can have literally morethan twice the flow, MFI=48 at almost the same molecular weight and areaccompanied by high impact strength with complete ductility, even at thereduced temperature of -10° C.

The essence of the invention is the insertion of the aliphatic alphaomega dicarboxylate unit into the polycarbonate, thereby providing acopolyestercarbonate having repeating units of the structure ##STR3##where R, R¹, n, n¹, W and b have been previously described and X is analiphatic grouping of about 8 to about 18 carbon atoms, inclusive. The drepeating unit is present in the copolyestercarbonate in from about 2 to30 mole percent of the total of the repeating units c+d, X is preferablyabout 10 to 18 carbon atoms, inclusive. The aliphatic system ispreferably saturated and is normal, branched, cyclic or alkylenesubstituted cyclic. The mole percent of d is preferably about 5 to 25and more preferably about 7 to 15 mole percent.

As shown in this specification, the copolyester carbonates of thisinvention essentially maintain a significant portion of the physicalproperties of polycarbonate of similar or same molecular weight butachieve these, except those related to Tg such as HDT, with reducedprocessing requirements since the Melt Flow Index for these newmaterials is substantially raised. Perhaps the most significant propertymaintained and in some cases even improved is the 1/8 inch Notched Izodimpact strength. Similarly, copolyestercarbonates of this inventionwhich have the same processability as standard polycarbonates can havesignificantly higher molecular weights and resulting propertyenhancements.

Thus, a further aspect of this invention is a method for using the aboveidentified invention compositions. This ks a method for processingresins which comprises processing a copolyestercarbonate of the aboveinvention wherein the copolyestercarbonate is processed at a temperaturesignificantly lower and with less work, as shown by a higher melt flowindex than the same aromatic polycarbonate without ester units and ofthe same weight average molecular weight. Any type of processingoperation is included for example, injection molding, rotary molding,blow molding, compression molding and extrusion processes such as sheetand film extrusion, profile extrusion, coextrusion and generalcompounding. Injection molding and extrusion are preferred.

When referring to the "polycarbonate of same or similar molecularweight" or "standard polycarbonate" reference is made to thepolycarbonate made from the same dihydric phenol but without aliphaticester repeat units.

Further examples of extruded articles of the copolyestercarbonate of theinvention include ordinary sheet articles, as well as multi walled sheetand film. Generally the thickness of an extruded article which is ofmaximum thickness to be called "film" is about 0.5-1 mum. The extrudedarticles need not be made of all copolyestercarbonate compositions ofthe invention. Rather such articles can be made from compositionscomprising at least 90% by weight of the inventioncopolyestercarbonates. Other polymers may be present in the composition.Preferred examples of such polymers are polyesters such as thepolyalkylene terephthalates, preferably polyethylene terephthalate andpolybutylene terephthalate, as well as cyclohexanedimethanol (CHDM)containing polyesters.

Examples of such polyesters include polyesters prepared from CHDM andterephthalic acid, mixtures of terephthalic acid and isophthalic acid,mixture of CHDM and alkylene glycol, preferably ethylene glycol, whereinthe CHDM is preferably from 20-80 mole % of the glycol present, theremainder being the alkylene glycol, preferably ethylene glycol. Theacid portion of the CHDM containing polyesters is terephthalic,isophthalic, mixtures thereof or preferably terephthalic. Examples ofsuch polesters all available from Eastman Chemical are PCT (100% CHDM,terephthalic acid), PCTG (80% CHDM, 20% ethylene glycol, terephthalicacid) and PETG (80% ethylene glycol, 20% CHDM, terephthalic acid).Thermoformed products are readily prepared from the sheet or film.

Surprisingly these extruded film or sheet products show some unexpectedadvantages as compared to extruded products made out of conventionalaromatic polycarbonates such as bisphenol-A polycarbonates.

Sheets extruded out of conventional aromatic polycarbonates require apredrying step before they can be thermoformed at elevated temperatures.If they are not predried, bubbling occurs at the surface of thethermoformed sheet.

It has been found that sheets extruded out of a thermoplasticcomposition based on the copolyestercarbonates of this invention do notrequire a predrying step before thermoforming.

It has further been found that sheets extruded out of a thermoplasticcomposition based on copolyestercarbonates of this invention are moreresistant in the flame retardancy test according to DIN 4102, ascompared to sheets extrude out of conventional aromatic polycarbonates.The test according to DIN 4102 is of importance for the building andconstruction industry.

Below are further examples of the invention. These examples are intendedto further illustrate the invention.

Example 10

Two series of sheets (with a thickness of 3 millimeters) have beenmanufactured by extrusion on a Werner Pfleiderer twin screw extruder.One series (A) of sheets has been manufactured out of a conventionalaromatic polycarbonate derived from bigphenol A and phosgene, with anintrinsic viscosity of 58 ml/g as measured in CH₂ CL₂ at 20° C. Thesecond series (B) of sheets has been manufactured out of acopolyestercarbonate according to the invention, with a dodecanedioic(HOOC[CH₂ ]₁₀ COOH ) content of 10 mole % based on dihydric phenol plusdiacid with an intrinsic viscosity of 58.2 ml/g as measured in CH₂ CL₂at 20° C.

The sheets were exposed to moisture and then thermo formed with a dryingstep prior to the thermoforming or no drying step. The thermoforming wasdone on a Geiss 1000×600 min. vacuum forming machine with an aluminiummold, hearted to 100° C. The sheets were heated by radiation prior tothermoforming. The radiation temperature is about 25° C above the actualtemperature of the sheet. The surface was examined after thermoforming.

The exact pretreatment, the radiation temperatures and the observedsurface quality are recorded in following table.

                  TABLE                                                           ______________________________________                                                             Radiation                                                                     tempera-                                                 Se-                  ture                                                     ries Pretreatment    °C.                                                                              Observations                                   ______________________________________                                        A    14 days at relative                                                                           212       Bubbling all over                                   humidities varying        the formed part,                                    from 58-79%, no           diameter 1 to                                       drying prior to           1.5 mm, average 8                                   thermoforming             bubbles/cm.sup.2.                                                   180       Forming not                                                                   possible.                                           Dried 24 hours 100 C.                                                                         212       No bubbles                                     B    14 days at relative                                                                           180       At all 4 tempera-                                   humidities varying                                                                            185       tures excellent                                     from 58-79%, no 190       formability and no                                  drying prior to 195       bubbling visible                                    thermoforming                                                                                 212       Some bubbling                                                                 noticed. Diameter                                                             0.5 mm, average 0.2                                                           bubbles/cm.sup.2.                                   Stored 14 days at                                                                             180       No bubbles,                                         relative humidity         excellent forming.                                  58-79%, then put                                                              under water during                                                                            190       Small bubbles                                       24 hrs at 21° C., no                                                                             0.5 mm diam., 0.3                                   drying prior to           bubbles/cm.sup.2                                    thermoforming                                                                                 211       Bubbles 1-1.5 mm,                                                             0.3 bubbles/cm.sup.2                                Dried 24 hours 100° C.                                                                 211       Excellent forming                                                             no bubbles.                                    ______________________________________                                    

As can be seen from the results reported in the table, the sheetaccording to the invention can, even when not predried be formed withoutbubbles. Additionally it appears that such thermoforming can be carriedout at a lower temperature than conventional polycarbonate.

Example 11

Sheets with a dimension of 190×1000×3 (ram) were extruded from apolyestercarbonate according to the an intrinsic viscosity of 58.2 ml/gas measured CH₂ CL₂ at 20° C.

The sheets were arranged in the lay-out specified for the B1 fire testaccording to DIN 4102, part 1 Brandschacht=chimney-test and were testedin unaged condition.

During the burning test the sheet according to the invention did notshow any gaseous development (bubbles) within the sheet, the specimendid not get ignited, there were no flaming drips and after the test theremaining length was 70 cm.

When sheet extruded out of conventional aromatic poly:, carbonate aresubjected to the same test, some gaseous development (bubbles) in thesheet occurs, the specimen gets ignited and there are flaming drips, Theremaining length is 40-60 cms.

Still further, a particularly preferred embodiment of the inventioncopolyestercarbonate that is the composition of the formula of FIG. 2and claim 14 composition wherein there is less than about 0.5 mole %,based on moles of dihydric phenol and discid in the polymer, ofanhydride present in the composition, It has surprisingly beendetermined that unless the pH ranges are maintained above 10, preferablyabout 11 at the latter part of the phosgenation period for a sufficientlength of time certain arthydride bonds will be formed and maintained inthe polymer. Although most impurities particularly at the low levelexperienced here do not adversely affect polymeric stability, theanhydride bonds are extremely harmful to the thermal stability of thecopolyestercarbonates of the invention.

The term "anhydride" means the diacid moiety of the polymer which has ananhydride linkage between it and a second acid moiety as illustratedbelow with dodecanedioic acid. ##STR4##

These anhydride bonds are formed during the polymerization reaction atthe lower pH range. It requires the higher pH range to bring about arearrangement of the polymer to remove the anhydride linkage and bringabout a more purified copolyestercarbonate composition.

The copolyestercarbonate of the invention should have less than 0.5 molepercent anhydride bonds, preferably less than 0.3 and more preferablyless than 0.1 mole percent anhydride bonds.

The anhydride bonds in the polymer can be detected by the use of highfield ¹ H NMR. Such NMR spectra were acquired using a 6 kHz sweep width,a 10s recycle delay, 30° C. flip angle, 16k memory size and 32transients taken on a GE NMR Omega-300 NMR Spectrometer. The spectrum ofa 10 mole % dodecanedioate bisphenol-A copolyestercarbonate prepared atthe lower pH and an inadequate amount of time at the higher pHdemonstrated anhydride bonds within the polymer. The ester tripletoccurred at 2.53 ppm. The arthydride triplet occurred at 2.43 ppm.

In each case the triplet is due to the methylene protons immediatelyadjacent to the carbonyl in the dodecanedioic acid moiety as shown bythe started methylene carbon atom below. ##STR5##

The presence of these anhydride bonds in the copolyestercarbonatepolymer are extremely injurious to the thermal stability of thecopolyestercarbonate of this invention. For example, ¹ H NMR spectra ofpowder and extruded pellets from the same lot of resin display differentcompositions. Under simple extrusion conditions, 230° C., thecopolyestercarbonate undergoes thermal degradation that appears toresult from the decomposition of the arthydride. Still further, theTable below shows the effect of anhydride bonds upon the melt viscosityas measured by Kasha Index, upon a series of 10 mole percentdodecanedioate containing bisphenol-A copolyestercarbonates with andwithout the measurable presence of anhydride bonds.

KI is measured in the following manner: 7 grams of resin pellets, drieda minimum of 90 minutes at 125° C., are added to a modified Tinius-Olsenmodel T3 melt indexer; the temperature in the indexer is maintained at300° C. and the resin is heated at this temperature for 6 minutes; after6 minutes the resin is forced through a 1,048 mm radius orifice using aplunger of radius of 4. 737 mm and an applied force of 8.03 kgf; thetime required for the plunger to travel 50.8mm is measured incentiseconds and this is reported as the KI.

    ______________________________________                                        Copolyester-                                                                  carbonate                Anhydride Bond                                                                           KI 6 Minute                               Sample   MW      Tg °C.                                                                         Present    Centisecond                               ______________________________________                                        A        27,400  126     Yes         310                                      B        24,700  127     No         1100                                      C        30,000  127     Yes         400                                      D        28,000  127     No         1700                                      E        32,300  127     Yes         500                                      F        31,000  127     No         3000                                      ______________________________________                                         As is readily apparent from the data, the presence of the anhydride bring     about substantial degradation of the polymer under the experimental           conditions.                                                              

The optimum methods of preparation which minimize presence of theanhydride bonds, usually below the higher field ¹ H NMR detection limitof 0.1 mole %, is the following.

The present optimum procedure for preparing copolyestercarbonates of theinvention minimize the anhydride present in the polymer and maximizesthe quantity of diacid incorporated into the polymer. A partialincorporation of the diacid not only affects the product consistency butthe unreacted diacid remains in the aqueous phase at the end of thereaction as the salt and can pose problems in the later treatment ofthat phase. Therefore the polymerization must be carried out in acertain pH range and certain time to allow the incorporation into thepolymer of the diacid but the pH must then be raised to a certain leveland for a sufficient length of time during the latter stages of thepolymerization to enable the anhydrides to be altered to ester bonds,thereby providing the invention copolyestercarbonate which isessentially anhydride free.

Generally with the passages of 1. 2 equivalents of phosgene per mole ofdihydric phenol and diacid, the pH of the phosgenation should bemaintained at about 8 for about 50-85% of the phosgenation time periodand then raised to about 11 over about a thirty second time period(small batch) for the remainder of the time period, about 15-50 percentof the time. The optimum time for increasing the pH appears to be atabout 70% of the phosgenation time period.

Of course, it is desirable to maximize the phosgenation rate so as tobring about a minimum reaction time which utilizes equipment mostproductively. The phosgenation rate can be increased substantially byintroducing to the reactor, a pre made solution of the salt of thediacid, preferably the sodium salt, as opposed to the diacid itself. Forexample when using reaction time of 26 minutes, 18 at pH 8, 8 at pH 11to prepare a 10 mole % dodecanedioate bisphenol-A copolyestercarbonatein a maxilab facility, a copolyester, carbonate with non detectablelevel of anhydride was formed leaving 74 ppm free diacid in the aqueousphase when introducing into the reactor a Solution of the disodio saltof dodecanedioic acid.

Experimentation in preparing the solution of the preferred disodio saltof the dodecanedioic acid (DDDA) indicate that smaller DDDA particlesize, lower percent solids and a slight excess of sodium hydroxide allcontribute to reduced dissolution times. Coarse, flaked DDDA takes morethan twice as long to dissolve than the granular material prepared bypulverization in a stainless steel Waring Blender. Below are theresults.

                                      TABLE                                       __________________________________________________________________________    Diacid                                                                             Particle                                                                            % Solids                                                                           NaOH/DDDA                                                                             Dissolution                                           Used Size  (wt/wt)                                                                            Mole ratio                                                                            Time (min)                                                                           Comments                                       __________________________________________________________________________    DDDA Granular.sup.b                                                                      13.3 2.5     >180   Slurry emulsion                                DDDA Granular.sup.b                                                                      7.0  2.5       7    Clear solution                                 DDDA Flaked.sup.c                                                                        7.0  2.5       16   Clear solution                                 DDDA Flaked.sup.c                                                                        7.0  5.0     >180   Slurry emulsion                                Azelaic.sup.a                                                                      Flaked.sup.d                                                                        7.0  2.5       17   Clear solution                                 __________________________________________________________________________     .sup.a Emerox 1144                                                            .sup.b 20-40 mesh                                                             .sup.c Flakes as large as 1/4 inch in diameter                                .sup.d Flakes as large as 1/2 inch in diameter                           

The solution addition of salt of diacid was verified in larger quantitypreparation of 9 mole % dodecanedioate bisphenol-A copolyestercarbonate.Adding about 111 pounds of phosgene in each reaction, the rate ofphosgenation was increased so as to bring down the reaction time. Ineach case the pH was held at 8 to 8.5 until 60 pounds of phosgene hadbeen transferred to the reactor. The pH was then ramped to 10.5-11 overthe next five minutes and held for the remainder of the reaction time.High field NMR did not detect any anhydride in the samples. Theincorporation of the DDDA was not seriously effected by the phosgenationrates. In the Table below pounds per hour is expressed as pph.

                  TABLE                                                           ______________________________________                                                pH Ramp    pH Ramp end Unreacted DDDA                                 Phosgene                                                                              Start (lbs (Lbs Phosgene)                                                                            in aqueous phase                               Rate (pph)                                                                            Phosgene)  (% reaction)                                                                              ppm                                            ______________________________________                                        190     60         77.5 (70)   47                                             220     60         77.7 (71)   27                                             260     60         86.1 (78)    5                                             330     60         92.0 (84)   NA                                             ______________________________________                                    

Articles molded or extruded from this copolyestercarbonate of theinvention having less than 0.5 mole percent anhydride have enhancedthermal stability. Examples of such copolyestercarbonate articles arewell known. These copolyestercarbonates may also have C₈ diacid(suberic) or C₉ diacid (azelaic) present in the copolyestercarbonate, asthe sole ester unit that is, the lower limit of the carbon number of thediacid incorporated is extended from C₁₀ to C₈ with the other variablesremaining the same. In FIG. 2, therefore, X would have a lower limit of6 carbon atoms. Polymers of the invention with less than about 500 ppmfree diacid in the aqueous phase are readily prepared.

What is claimed is:
 1. A composition comprising a copolyestercarbonatederived from a dihydric phenol, a carbonate precursor, and from about 2to 30 mole percent based on the dihydric phenol of an aliphatic alphaomega dicarboxylic acid or ester precursor wherein the dicarboxylic acidor ester precursor has from 8 to about 20 carbon atoms, inclusive,wherein the copolyestercarbonate is endcapped with a monophenoliccompound which provides the copolyestercarbonate with better notchedizod impact resistance and ductility after aging than phenol endcappedcopolyestercarbonate.
 2. The composition in accordance with claim 1wherein the dicarboxylic acid or ester precursor has from 8 to about 14carbon atoms, inclusive.
 3. The composition in accordance with claim 1wherein the mole percent is from about 8 to 15 mole percent.
 4. Thecomposition in accordance with claim 1 wherein the copolyestercarbonateis endcapped with a compound selected from the group consisting ofisooctylphenol, isononylphenol, cumylphenol or a chromanyl compound. 5.The composition in accordance with claim 4 wherein the compound isparacumnylphenol.
 6. The composition in accordance with claim 1 whereinthe diacid is azelaic.
 7. A method for processing a resin having similarmolecular weight to a standard polycarbonate resin which comprisesprocessing a copolyestercarbonate having repeat units of the structure##STR6## wherein: R is independently selected from halogen, monovalenthydrocarbon, and monovalent hydrocarbonoxy radicals;R¹ is independentlyselected from halogen, monovalent hydrocarbon, and monovalenthydrocarbonoxy radicals; W is selected from divalent hydrocarbonradicals, ##STR7## n and n¹ are independently selected from integershaving a value of from 0 to 4 inclusive; b is either zero or one; X isan aliphatic group of about 6 to 18 carbon atoms, inclusive; c is fromabout 2 to 30 mole percent of the total units c+d; andwith less workthan required for the said standard polycarbonate.
 8. A compositioncomprising a copolyestercarbonate derived from a dihydric phenol, acarbonate precursor, and from about 2 to 30 mole percent based on thedihydric phenol of an aliphatic alpha omega dicarboxylic acid or esterprecursor wherein the dicarboxylic acid or ester precursor has from 8 toabout 20 carbon atoms, inclusive, wherein the copolyestercarbonate isendcapped with a monophenolic compound which is bulkier than pure phenoland which provides the copolyestercarbonate with better notched izodimpact resistance and ductility after aging than a phenol endcappedcopolyestercarbonate.